MCP Server

FitSignal is a product-market fit measurement platform with a hosted MCP (Model Context Protocol) server. Connect any MCP client — Claude, Cursor, VS Code — and query your PMF data in natural language.

Connection

The FitSignal MCP server is hosted — there is nothing to install or run yourself.

Endpoint	`https://www.fitsignal.com/api/mcp`
Transport	Streamable HTTP
Authentication	API key (Bearer)
Coverage	Full parity with the REST v1 API

Authentication

The MCP server uses the same API keys as the REST v1 API. Create a key at Dashboard → Settings → API keys (starts with fs_live_ or fs_test_). The key needs the API scope.

Send the key in the Authorization header:

Authorization: Bearer fs_live_your_key

The X-FitSignal-Key: fs_live_your_key header also works if your client cannot set an Authorization header.

Client Setup

Configuration for the most common MCP clients. In each snippet, replace fs_live_your_key with your own API key.

Claude Code

Add the server from your terminal:

claude mcp add --transport http fitsignal https://www.fitsignal.com/api/mcp --header "Authorization: Bearer fs_live_your_key"

Claude Desktop / claude.ai

Custom connectors need OAuth

The claude.ai and Claude Desktop connector settings only support OAuth, and the FitSignal MCP server is API-key only today (OAuth support is planned). Until then, use Claude Code above — or bridge Claude Desktop through mcp-remote below.

Claude Desktop can connect via the mcp-remote bridge in claude_desktop_config.json:

{
  "mcpServers": {
    "fitsignal": {
      "command": "npx",
      "args": [
        "mcp-remote",
        "https://www.fitsignal.com/api/mcp",
        "--header",
        "Authorization: Bearer fs_live_your_key"
      ]
    }
  }
}

Cursor

Add to .cursor/mcp.json:

{
  "mcpServers": {
    "fitsignal": {
      "url": "https://www.fitsignal.com/api/mcp",
      "headers": {
        "Authorization": "Bearer fs_live_your_key"
      }
    }
  }
}

VS Code

Add to .vscode/mcp.json:

{
  "servers": {
    "fitsignal": {
      "type": "http",
      "url": "https://www.fitsignal.com/api/mcp",
      "headers": {
        "Authorization": "Bearer fs_live_your_key"
      }
    }
  }
}

ChatGPT

Not supported yet

ChatGPT connectors require OAuth; the FitSignal MCP server is API-key only today. OAuth support is planned.

Available Tools

Every tool maps 1:1 to a REST v1 endpoint, with the same inputs and outputs.

Tool	REST equivalent	Description
fitsignal_list_customers	`GET /v1/customers`	List customers with filters and pagination
fitsignal_get_customer	`GET /v1/customers/:id`	Get one customer by id or externalId
fitsignal_create_customer	`POST /v1/customers`	Create or update a customer (upsert by email)
fitsignal_update_customer	`PATCH /v1/customers/:id`	Update customer fields
fitsignal_delete_customer	`DELETE /v1/customers/:id`	Soft-delete a customer
fitsignal_bulk_upsert_customers	`POST /v1/customers/bulk`	Upsert up to 100 customers
fitsignal_list_surveys	`GET /v1/surveys`	List surveys in the project
fitsignal_get_survey	`GET /v1/surveys/:id`	Survey with questions and settings
fitsignal_send_survey	`POST /v1/surveys/:id/send`	Email invitations to up to 100 customers (paid plans)
fitsignal_list_responses	`GET /v1/responses`	List responses (lean rows; include_answers opt-in)
fitsignal_get_response	`GET /v1/responses/:id`	One response with full answers
fitsignal_get_pmf_score	`GET /v1/analytics/pmf`	PMF score, distribution, confidence, 40% benchmark
fitsignal_get_pmf_trends	`GET /v1/analytics/trends`	PMF score over time (weekly/monthly)

Clients discover tools automatically at connect time, so the list may grow without any configuration changes on your side.

Example Prompts

Once connected, try asking your MCP client things like:

"What's our PMF score trending this quarter?"
"Which customers answered 'very disappointed' last month?"
"Add jane@acme.com to FitSignal and send her the onboarding survey."
"How many responses came in through the widget vs email?"
"Summarize the answers from last week's responses."
"List surveys that are still collecting responses."

Rate Limits

The MCP server shares one rate limit pool with the REST v1 API: 100,000 requests per hour per API key, measured over a sliding window. REST calls and MCP tool calls draw from the same budget — an agent making many tool calls draws down the same allowance as your REST integration.

Every response includes the standard headers:

Header	Description
X-RateLimit-Limit	Total requests allowed in the window
X-RateLimit-Remaining	Requests left in the current window
X-RateLimit-Reset	When the window resets

Troubleshooting

401 Unauthorized

The Authorization header is missing or malformed — it must be exactly Bearer fs_live_your_key
The key has been revoked
The key lacks the API scope

429 Too Many Requests

You are over the hourly window. Back off until the time in the X-RateLimit-Reset header before retrying.

Tools not appearing

Check the exact URL: https://www.fitsignal.com/api/mcp
The transport must be HTTP (Streamable HTTP), not SSE
Restart the client after config changes